High-temperature steam reforming process design

Based on the type of thermal destruction process selected, there are several different commercial designs and configurations of the reactor that have been utilized for a particular application. Some of the most commonly used technologies include rotary kilns, starved air incinerators, fluidized beds, mass-bum incinerators, electrically heated reactors, microwave reactors, plasma, and other high-temperature thermal destruction systems. Recent advances include gasification and very high temperature steam reforming. 

Description Natural gas or another hydrocarbon feedstock is compressed (if required), desulfurized, mixed with steam and then converted into synthesis gas. The reforming section comprises a prereformer (optional, but gives particular benefits when the feedstock is higher hydrocarbons or naphtha), a fired tubular reformer and a secondary reformer, where process air is added. The amount of air is adjusted to obtain an H2/N2 ratio of 3.0 as required by the ammonia synthesis reaction. The tubular steam reformer is Topsoe s proprietary side-wall-fired design. After the reforming section, the synthesis gas undergoes high- and low-temperature shift conversion, carbon dioxide removal and methanation. 

Mechanical strength and thermal stability of catalyst particles are always of concern to process designers. In some cases it may be the most critical feature. This was emphasized, for e.xample, in steam reforming. Strong pellets with good thermal resistance are required. Catalyst designers use mixed oxides fired at high temperatures to form ceramic compounds, Particles must be preformed and active components added later. 

Nuclear reformer tube heating with a high-temperature reactor is performed with helium, typically at 950 °C, as the heat source. A counterflow scheme allows the use of internal return pipes for the product gas. Experience in construction and operation was gained with the EVA-I and EVA-II facilities at the Research Center Jiilich. The perceived disadvantages of a nuclear steam reformer with its comparatively low heat transfer and its high system pressure can be overcome by design optimization to increase heat input into the process gas and its conversion rate. 

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